This invention relates to improvements in strain gages for measuring strain in a body subjected to variable stress and, more particularly, to strain gages of the type comprising a strain-responsive filament coupled to a strain-deformable housing which is adapted for welding to a test member.
Strain gages of the resistance wire type have been in use for some time for measuring variable quantities such as strain, pressure, torque, acceleration and temperature. The typical resistance wire strain gage contains a resistance wire connected in a conventional four-arm bridge circuit which ordinarily is balanced. The force to be measured is coupled mechanically to the resistance wire by various means, such that the force exerted on the wire through the coupling means causes the dimensions of the wire to be altered, which results in a proportional change in the resistance of the wire. This in turn causes unbalancing of the bridge in an amount at least roughly proportional to the force applied to the wire.
The present invention is summarized in that a weldable strain gage comprises a strain-responsive carbon filament mechanically coupled to a strain-deformable housing.
It is an object of the present invention to provide a weldable strain gage having a strain-responsive carbon filament for use at relatively high temperatures.
It is a further object of the present invention to provide a weldable strain gage having a strain-responsive carbon filament for use at ambient temperatures.
It is a further object of the present invention to provide a weldable strain gage having a strain-responsive carbon filament wherein the coupling between the strain-responsive carbon filament and the strain-deformable housing is mechanical, or adhesive, or both mechanical and adhesive.